Q: I am a puzzled editor. I cringe every time I see the word “insure” used in a non-financial sense in respected publications. I am under the impression (perhaps mistakenly) that “insure” should be used in regard to finances, and “ensure” in a more abstract and wider sense. I would appreciate any light that you can shed on this.
A: In the US, both “ensure” and “insure” can mean to make certain of something, but “insure” is preferred in the commercial sense (to issue or take out insurance). All five American standard dictionaries that we regularly consult agree on this, while the five British dictionaries we consult describe it as standard in the US.
Nevertheless, some usage and style manuals insist that “insure” should be used only in the financial sense.
A third verb, “assure,” is often confused with “ensure” and “insure.” In both the US and the UK, “assure” means to set someone’s mind at rest, though it’s sometimes used in the UK to mean underwrite financial loss.
All three verbs—“assure,” “ensure,” and “insure”—have their roots in a Latin word for “safe” or “secure.”